onscroll = function(){
var st = document.documentElement.scrollTop || document.body.scrollTop;
    {
        if(!fix.offsetWidth && st >= 900)
        {
            fix.style.display = "flex";
        }
        else if(!!fix.offsetWidth && st < 900)
        {
        fix.style.display = "none";
        }
    }
    {
        if(!comeback.offsetWidth && st >= 500)
        {
            comeback.style.display = "flex";
        }
        else if(!!comeback.offsetWidth && st < 500)
        {
        comeback.style.display = "none";
        }
    }
}
var NAV = document.querySelectorAll('.head-nav a span')
for (var i = 0,len = NAV.length;i < len;i++){
    NAV[i].addEventListener("click",function(event){
        for (var j = 0;j < NAV.length;j++){
            if(NAV[j].classList.contains("add-border")){
                NAV[j].classList.remove("add-border")
            }
        }
        this.classList.add("add-border")
    },false)
}
var FIXNAV = document.querySelectorAll('.fixhead-nav a span')
for (var i = 0,len = FIXNAV.length;i < len;i++){
    FIXNAV[i].addEventListener("click",function(event){
        for (var j = 0;j < FIXNAV.length;j++){
            if(FIXNAV[j].classList.contains("addBorder")){
                FIXNAV[j].classList.remove("addBorder")
            }
        }
        this.classList.add("addBorder")
    },false)
}